1. Field of the Invention
The present invention relates generally to methods for accessing information stored in a database management system (DBMS), and in particular, to a generic query agent for providing optimized remote user access to database management systems.
2. Description of the Related Art
Large-scale integrated database management systems provide an efficient, consistent, and secure means for storing and retrieving vast amounts of data. This ability to manage massive amounts of information has become a virtual necessity in business today.
Usually, the process of obtaining information from the DBMS is highly interactive, requiring short periods of high bandwidth, low-latency communications between the end user and the DBMS, followed by extended periods with little or no communications traffic. Because local area network (LAN) or wide area network (WAN) communications are high bandwidth and low cost, the user is typically provided access to the database via a desktop computer coupled directly by a (LAN) or a laptop computer coupled to the LAN via the Public Switched Telephone Network (PSTN). This arrangement is the well known client-server architecture.
Businesses using integrated database management systems (DBMSs) have become increasingly mobile and service-oriented, raising the need for timely and inexpensive mobile access to database information. Mobile users also frequently require access to information which is stored in different DMBSs. Mobile communications are available through cellular telephone, paging, and other radio networks, but using these communication links for providing access to DBMSs is problematic. Cellular telephone communications offer low bandwidth, are quite expensive, and often unreliable. Remote paging networks provide inexpensive reliable communications, but at the cost of low-bandwidth and high data latency. Therefore, there is a widely recognized need to provide an interface between mobile users and DBMSs using low bandwidth, high-latency mobile communication links.
A prior art solution to this problem is to implement client-agent-server (CAS) architecture, in which an agent's application is inserted between the mobile client application and the server. One example of such a system is Oracle in Motion.TM. produced by the Oracle Corporation. In a client-agent-server architecture, clients communicate with the agent via mobile communications link, causing the agent to execute work on behalf of the client. The results of the agent's work is bundled into a single message and transmitted back to the client application where the results are displayed. By providing an asynchronous link, the shortcomings of the mobile link are reduced.
These prior art CAS architectures use a system-level approach to accomplish this task, using the combination of many components distributed throughout the network, including the mobile user and the database server. While these prior art systems reduce use of the mobile link by sending the results in a single message, this simple communication scheme is inadequate when dealing with a broad range of mobile users and database resources, and does not take advantage of the additional information available to the query agent to fully optimize communications.